Spiderweb-structured aerogels with high-efficiency microwave absorption and multifunctionality

Optimizing the dispersion of single-walled carbon nanotubes (SWCNTs) within cellulose nanofiber (CNF) aerogels is pivotal for achieving enhanced microwave absorption and multifunctionality. Equally important is ensuring the mechanical durability and long-term stability of these materials. Here, a fabrication strategy that combines ball-milling-assisted mono-dispersion and self-assembly techniques was reported to optimize the structure of aerogels. The SWCNTs are uniformly dispersed through electrostatic repulsion and steric hindrance during ball milling, while the self-assembly process modifies the internal hydrogen bonding of CNFs to prevent excessive densification. This dual approach facilitates the formation of a three-dimensional (3D) network via physical entanglement between SWCNTs and CNFs. Subsequent directional freeze-drying yields lightweight, elastic composite aerogels featuring a biomimetic spiderweb-like structure. The optimized aerogels exhibit outstanding electromagnetic wave (EMW) absorption properties, achieving a minimum reflection loss (RL_min) of −38.9 dB, an effective absorption bandwidth (EAB) of 8.5 GHz, and a maximum radar cross-section (RCS) reduction of 34.44 dB·m². Additionally, these aerogels exhibit remarkable mechanical resilience, retaining up to 86.1 % stress over 50 compression cycles at extreme conditions (-20°C). Combined with their superior thermal insulation and thermal infrared performance, these aerogels offer significant potential for advanced EMW management and multifunctional applications.